[Fix] Fix background heartbeat requests falling back to the default Twinkle server URL

src/twinkle_client/http/heartbeat.py

@@ -4,7 +4,7 @@
 from typing import Callable, Dict, Optional, Set
 
 from .http_utils import http_post
-from .utils import TWINKLE_SERVER_URL
+from .utils import get_base_url
 
 
 class HeartbeatManager:
@@ -33,7 +33,6 @@ def __init__(self):
             return
 
         self._initialized = True
-        self.server_url = TWINKLE_SERVER_URL
 
         # Processor heartbeat management
         self.processor_ids: Set[str] = set()
@@ -52,7 +51,7 @@ def __init__(self):
 
     def processor_heartbeat_func(self, processor_id_list: str):
         response = http_post(
-            url=f'{self.server_url}/processors/heartbeat', json_data={'processor_id': processor_id_list})
+            url=f'{get_base_url()}/processors/heartbeat', json_data={'processor_id': processor_id_list})
         response.raise_for_status()
 
     def register_processor(self, processor_id: str):

src/twinkle_client/http/utils.py

@@ -11,24 +11,33 @@
 _base_url_context: ContextVar[Optional[str]] = ContextVar('base_url', default=None)
 _api_key_context: ContextVar[Optional[str]] = ContextVar('api_key', default=None)
 
+# Global fallback for base_url, accessible from all threads (including heartbeat daemon threads).
+# ContextVar is thread-local and invisible to background threads, so we also store the URL here.
+_global_base_url: Optional[str] = None
+
 # Global static request ID shared across all threads
 # This ensures heartbeat threads use the same request ID as the main training thread
 _global_request_id: Optional[str] = None
 
 
 def set_base_url(url: str):
-    """Set the base URL for HTTP requests in the current context."""
-    _base_url_context.set(url.rstrip('/'))
+    """Set the base URL for HTTP requests in the current context and globally."""
+    global _global_base_url
+    stripped = url.rstrip('/')
+    _base_url_context.set(stripped)
+    _global_base_url = stripped
 
 
 def get_base_url() -> Optional[str]:
-    """Get the current base URL from context or environment variable."""
-    return _base_url_context.get() or TWINKLE_SERVER_URL
+    """Get the current base URL from context, global fallback, or environment variable."""
+    return _base_url_context.get() or _global_base_url or TWINKLE_SERVER_URL
 
 
 def clear_base_url():
-    """Clear the base URL context, falling back to environment variable."""
+    """Clear the base URL context and global fallback, falling back to environment variable."""
+    global _global_base_url
     _base_url_context.set(None)
+    _global_base_url = None
 
 
 def set_api_key(api_key: str):